检查元素是否在数组中两次 [英] Check if element is in array twice time

问题描述

我需要知道元素是否在数组中两次或多次。

I need to know if an element is in array twice or many time.

var arr = [elm1,elm2,elm3,elm3,elm4,elm5,elm5,elm5,elm6,elm7] ;
if(elm is in array by many time ){
      // do some code with this element
}else{
      // other stuff ;;
}

有什么建议吗？

推荐答案

countInArray函数可能是你的选项

The countInArray function may be an option for you

function countInArray(array, what) {
    return array.filter(item => item == what).length;
}

或类似的东西，这可能会更好地理解代码和调整你想要的东西！ ：

Or something like this, this may be better for you to understand the code and adjust somethings where you want to! :

var list = [2, 1, 4, 2, 1, 1, 4, 5];  

function countInArray(array, what) {
    var count = 0;
    for (var i = 0; i < array.length; i++) {
        if (array[i] === what) {
            count++;
        }
    }
    return count;
}

countInArray(list, 2); // returns 2
countInArray(list, 1); // returns 3

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